ieee802154: enable smart transmitter features of RF212

This patch does multiple things:

 * add .set_csma_params and .set_frame_retries for the RF212 radio.
   This should work fine with RF230, but since I have no RF230 radios to
   test with, RF230 does not implement these right now
 * enable TX_ARET for frame retransmission limits greater than -1

Since RF230 has no operations to change CSMA parameters or frame retry
limits, RF230 will not be able to enter TX_ARET with this patch.
Signed-off-by: Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ieee802154/at86rf230.c

@@ -52,6 +52,7 @@ struct at86rf230_local {
 	spinlock_t lock;
 	bool irq_busy;
 	bool is_tx;
+	bool tx_aret;
 
 	int rssi_base_val;
 };
@@ -549,7 +550,9 @@ at86rf230_state(struct ieee802154_dev *dev, int state)
 	} while (val == STATE_TRANSITION_IN_PROGRESS);
 
 
-	if (val == desired_status)
+	if (val == desired_status ||
+	    (desired_status == STATE_RX_ON && val == STATE_BUSY_RX) ||
+	    (desired_status == STATE_RX_AACK_ON && val == STATE_BUSY_RX_AACK))
 		return 0;
 
 	pr_err("unexpected state change: %d, asked for %d\n", val, state);
@@ -570,6 +573,10 @@ at86rf230_start(struct ieee802154_dev *dev)
 	if (rc)
 		return rc;
 
+	rc = at86rf230_state(dev, STATE_FORCE_TX_ON);
+	if (rc)
+		return rc;
+
 	return at86rf230_state(dev, STATE_RX_AACK_ON);
 }
 
@@ -669,6 +676,12 @@ at86rf230_xmit(struct ieee802154_dev *dev, struct sk_buff *skb)
 	if (rc)
 		goto err_rx;
 
+	if (lp->tx_aret) {
+		rc = at86rf230_write_subreg(lp, SR_TRX_CMD, STATE_TX_ARET_ON);
+		if (rc)
+			goto err_rx;
+	}
+
 	rc = at86rf230_write_subreg(lp, SR_TRX_CMD, STATE_BUSY_TX);
 	if (rc)
 		goto err_rx;
@@ -823,6 +836,44 @@ at86rf212_set_cca_ed_level(struct ieee802154_dev *dev, s32 level)
 	return at86rf230_write_subreg(lp, SR_CCA_ED_THRES, desens_steps);
 }
 
+static int
+at86rf212_set_csma_params(struct ieee802154_dev *dev, u8 min_be, u8 max_be,
+			  u8 retries)
+{
+	struct at86rf230_local *lp = dev->priv;
+	int rc;
+
+	if (min_be > max_be || max_be > 8 || retries > 5)
+		return -EINVAL;
+
+	rc = at86rf230_write_subreg(lp, SR_MIN_BE, min_be);
+	if (rc)
+		return rc;
+
+	rc = at86rf230_write_subreg(lp, SR_MAX_BE, max_be);
+	if (rc)
+		return rc;
+
+	return at86rf230_write_subreg(lp, SR_MAX_CSMA_RETRIES, max_be);
+}
+
+static int
+at86rf212_set_frame_retries(struct ieee802154_dev *dev, s8 retries)
+{
+	struct at86rf230_local *lp = dev->priv;
+	int rc = 0;
+
+	if (retries < -1 || retries > 15)
+		return -EINVAL;
+
+	lp->tx_aret = retries >= 0;
+
+	if (retries >= 0)
+		rc = at86rf230_write_subreg(lp, SR_MAX_FRAME_RETRIES, retries);
+
+	return rc;
+}
+
 static struct ieee802154_ops at86rf230_ops = {
 	.owner = THIS_MODULE,
 	.xmit = at86rf230_xmit,
@@ -845,6 +896,8 @@ static struct ieee802154_ops at86rf212_ops = {
 	.set_lbt = at86rf212_set_lbt,
 	.set_cca_mode = at86rf212_set_cca_mode,
 	.set_cca_ed_level = at86rf212_set_cca_ed_level,
+	.set_csma_params = at86rf212_set_csma_params,
+	.set_frame_retries = at86rf212_set_frame_retries,
 };
 
 static void at86rf230_irqwork(struct work_struct *work)
@@ -921,6 +974,7 @@ static int at86rf230_hw_init(struct at86rf230_local *lp)
 	struct at86rf230_platform_data *pdata = lp->spi->dev.platform_data;
 	int rc, irq_pol;
 	u8 status;
+	u8 csma_seed[2];
 
 	rc = at86rf230_read_subreg(lp, SR_TRX_STATUS, &status);
 	if (rc)
@@ -944,6 +998,14 @@ static int at86rf230_hw_init(struct at86rf230_local *lp)
 	if (rc)
 		return rc;
 
+	get_random_bytes(csma_seed, ARRAY_SIZE(csma_seed));
+	rc = at86rf230_write_subreg(lp, SR_CSMA_SEED_0, csma_seed[0]);
+	if (rc)
+		return rc;
+	rc = at86rf230_write_subreg(lp, SR_CSMA_SEED_1, csma_seed[1]);
+	if (rc)
+		return rc;
+
 	/* CLKM changes are applied immediately */
 	rc = at86rf230_write_subreg(lp, SR_CLKM_SHA_SEL, 0x00);
 	if (rc)